pthread condition vars - Doh!

[Robert Collins]

I've just found out that SignalObjectAndWait, which I use in several
locations in the pthreads code, is not available on 9x platforms.
SignalObjectAndWait is the appropriate function to prevent races for
emulated posix objects that involve more than 1 win32 object.

For the short-term I'm simply planning to break open the function into
two separate calls. (For win9x platforms only). This does introduce a
race. Longer term I'm going to sit down and do a little research :]

It's quite important I get a workaround in place before 1.3.0 goes out,
even if it has a race it'll let the code run on win9x.

Rob